src/newgrf_storage.h

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   6  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   7  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   8  */
   9
  10 /** @file newgrf_storage.h Functionality related to the temporary and persistent storage arrays for NewGRFs. */
  11
  12 #ifndef NEWGRF_STORAGE_H
  13 #define NEWGRF_STORAGE_H
  14
  15 #include "core/pool_type.hpp"
  16 #include "map/coord.h"
  17
  18 /**
  19  * Mode switches to the behaviour of persistent storage array.
  20  */
  21 enum PersistentStorageMode {
  22         PSM_ENTER_GAMELOOP,   ///< Enter the gameloop, changes will be permanent.
  23         PSM_LEAVE_GAMELOOP,   ///< Leave the gameloop, changes will be temporary.
  24         PSM_ENTER_COMMAND,    ///< Enter command scope, changes will be permanent.
  25         PSM_LEAVE_COMMAND,    ///< Leave command scope, revert to previous mode.
  26         PSM_ENTER_TESTMODE,   ///< Enter command test mode, changes will be tempoary.
  27         PSM_LEAVE_TESTMODE,   ///< Leave command test mode, revert to previous mode.
  28 };
  29
  30 /**
  31  * Base class for all persistent NewGRF storage arrays. Nothing fancy, only here
  32  * so we have a generalised access to the virtual methods.
  33  */
  34 struct BasePersistentStorageArray {
  35         uint32 grfid;    ///< GRFID associated to this persistent storage. A value of zero means "default".
  36         byte feature;    ///< NOSAVE: Used to identify in the owner of the array in debug output.
  37         TileIndex tile;  ///< NOSAVE: Used to identify in the owner of the array in debug output.
  38
  39         virtual ~BasePersistentStorageArray();
  40
  41         static void SwitchMode(PersistentStorageMode mode, bool ignore_prev_mode = false);
  42
  43 protected:
  44         /**
  45          * Discard temporary changes.
  46          */
  47         virtual void ClearChanges() = 0;
  48
  49         /**
  50          * Check whether currently changes to the storage shall be persistent or
  51          * temporary till the next call to ClearChanges().
  52          */
  53         static bool AreChangesPersistent() { return (gameloop || command) && !testmode; }
  54
  55 private:
  56         static bool gameloop;
  57         static bool command;
  58         static bool testmode;
  59 };
  60
  61 /**
  62  * Class for persistent storage of data.
  63  * On #ClearChanges that data is either reverted or saved.
  64  * @tparam TYPE the type of variable to store.
  65  * @tparam SIZE the size of the array.
  66  */
  67 template <typename TYPE, uint SIZE>
  68 struct PersistentStorageArray : BasePersistentStorageArray {
  69         TYPE storage[SIZE]; ///< Memory to for the storage array
  70         TYPE *prev_storage; ///< Memory to store "old" states so we can revert them on the performance of test cases for commands etc.
  71
  72         /** Simply construct the array */
  73         PersistentStorageArray() : prev_storage(NULL)
  74         {
  75                 memset(this->storage, 0, sizeof(this->storage));
  76         }
  77
  78         /** And free all data related to it */
  79         ~PersistentStorageArray()
  80         {
  81                 free(this->prev_storage);
  82         }
  83
  84         /** Resets all values to zero. */
  85         void ResetToZero()
  86         {
  87                 memset(this->storage, 0, sizeof(this->storage));
  88         }
  89
  90         /**
  91          * Stores some value at a given position.
  92          * If there is no backup of the data that backup is made and then
  93          * we write the data.
  94          * @param pos   the position to write at
  95          * @param value the value to write
  96          */
  97         void StoreValue(uint pos, int32 value)
  98         {
  99                 /* Out of the scope of the array */
 100                 if (pos >= SIZE) return;
 101
 102                 /* The value hasn't changed, so we pretend nothing happened.
 103                  * Saves a few cycles and such and it's pretty easy to check. */
 104                 if (this->storage[pos] == value) return;
 105
 106                 /* We do not have made a backup; lets do so */
 107                 if (AreChangesPersistent()) {
 108                         assert(this->prev_storage == NULL);
 109                 } else if (this->prev_storage == NULL) {
 110                         this->prev_storage = MallocT<TYPE>(SIZE);
 111                         memcpy(this->prev_storage, this->storage, sizeof(this->storage));
 112
 113                         /* We only need to register ourselves when we made the backup
 114                          * as that is the only time something will have changed */
 115                         AddChangedPersistentStorage(this);
 116                 }
 117
 118                 this->storage[pos] = value;
 119         }
 120
 121         /**
 122          * Gets the value from a given position.
 123          * @param pos the position to get the data from
 124          * @return the data from that position
 125          */
 126         TYPE GetValue(uint pos) const
 127         {
 128                 /* Out of the scope of the array */
 129                 if (pos >= SIZE) return 0;
 130
 131                 return this->storage[pos];
 132         }
 133
 134         void ClearChanges()
 135         {
 136                 if (this->prev_storage != NULL) {
 137                         memcpy(this->storage, this->prev_storage, sizeof(this->storage));
 138                         free(this->prev_storage);
 139                         this->prev_storage = NULL;
 140                 }
 141         }
 142 };
 143
 144
 145 /**
 146  * Class for temporary storage of data.
 147  * On #ClearChanges that data is always zero-ed.
 148  * @tparam TYPE the type of variable to store.
 149  * @tparam SIZE the size of the array.
 150  */
 151 template <typename TYPE, uint SIZE>
 152 struct TemporaryStorageArray {
 153         TYPE storage[SIZE]; ///< Memory to for the storage array
 154         uint16 init[SIZE];  ///< Storage has been assigned, if this equals 'init_key'.
 155         uint16 init_key;    ///< Magic key to 'init'.
 156
 157         /** Simply construct the array */
 158         TemporaryStorageArray()
 159         {
 160                 memset(this->storage, 0, sizeof(this->storage)); // not exactly needed, but makes code analysers happy
 161                 memset(this->init, 0, sizeof(this->init));
 162                 this->init_key = 1;
 163         }
 164
 165         /**
 166          * Stores some value at a given position.
 167          * @param pos   the position to write at
 168          * @param value the value to write
 169          */
 170         void StoreValue(uint pos, int32 value)
 171         {
 172                 /* Out of the scope of the array */
 173                 if (pos >= SIZE) return;
 174
 175                 this->storage[pos] = value;
 176                 this->init[pos] = this->init_key;
 177         }
 178
 179         /**
 180          * Gets the value from a given position.
 181          * @param pos the position to get the data from
 182          * @return the data from that position
 183          */
 184         TYPE GetValue(uint pos) const
 185         {
 186                 /* Out of the scope of the array */
 187                 if (pos >= SIZE) return 0;
 188
 189                 if (this->init[pos] != this->init_key) {
 190                         /* Unassigned since last call to ClearChanges */
 191                         return 0;
 192                 }
 193
 194                 return this->storage[pos];
 195         }
 196
 197         void ClearChanges()
 198         {
 199                 /* Increment init_key to invalidate all storage */
 200                 this->init_key++;
 201                 if (this->init_key == 0) {
 202                         /* When init_key wraps around, we need to reset everything */
 203                         memset(this->init, 0, sizeof(this->init));
 204                         this->init_key = 1;
 205                 }
 206         }
 207 };
 208
 209 void AddChangedPersistentStorage(BasePersistentStorageArray *storage);
 210
 211 typedef PersistentStorageArray<int32, 16> OldPersistentStorage;
 212
 213 typedef uint32 PersistentStorageID;
 214
 215 /**
 216  * Class for pooled persistent storage of data.
 217  */
 218 struct PersistentStorage : PersistentStorageArray<int32, 16>, PooledItem <PersistentStorage, PersistentStorageID, 1, 0xFF000> {
 219         /** We don't want GCC to zero our struct! It already is zeroed and has an index! */
 220         PersistentStorage(const uint32 new_grfid, byte feature, TileIndex tile)
 221         {
 222                 this->grfid = new_grfid;
 223                 this->feature = feature;
 224                 this->tile = tile;
 225         }
 226 };
 227
 228 assert_compile(cpp_lengthof(OldPersistentStorage, storage) == cpp_lengthof(PersistentStorage, storage));
 229
 230 #define FOR_ALL_STORAGES_FROM(var, start) FOR_ALL_ITEMS_FROM(PersistentStorage, storage_index, var, start)
 231 #define FOR_ALL_STORAGES(var) FOR_ALL_STORAGES_FROM(var, 0)
 232
 233 #endif /* NEWGRF_STORAGE_H */